Field
Examples of the present disclosure generally relate to semiconductor manufacturing processes, more particularly, to methods for gapfilling high aspect ratio trenches of semiconductor devices with amorphous silicon film, and devices formed by the methods.
Description of the Related Art
For many semiconductor device manufacturing processes, there is a need to fill narrow trenches having high aspect ratios greater than, for example, 10:1, with no voiding. One example of such a process is shallow trench isolation (STI) in which the film needs to be of high quality and have very low leakage throughout the trench. As the dimensions of semiconductor device structures continue to decrease and the aspect ratios increase, post-curing processes become increasingly difficult and result in films with varying composition throughout the filled trench.
Conventionally, amorphous silicon (a-Si) has been used in semiconductor manufacturing processes since a-Si generally provides good etch selectivity with respect to other films, such as silicon oxide (SiO) and amorphous carbon (a-C). The conventional a-Si deposition methods, such as plasma-enhanced chemical vapor deposition (PECVD) and conformal deposition, however, cannot be used to gapfill high aspect ratio trenches because a seam forms in the high aspect ratio trenches. A seam may result in the formation of one or more gaps in the trench between the sidewalls, which may be further opened up during post-curing processes. Such seems and gaps ultimately cause decreased throughput or even semiconductor device failure. Additionally, PECVD of a-Si may also result in voiding at the bottom of the trench, which may also result in semiconductor device failure.
Additionally, the success of gapfilling high aspect ratio trenches with a-Si depends on the nature of the underlying surface. For example, when the underlying surface is hydroxy-terminated silicon (Si—OH), or hydrogen-terminated silicon (Si—H), microporosity and microvoiding has been observed.
Therefore, there is a need for methods for gapfilling high aspect ratio trenches of semiconductor devices that can provide seam-free and void-free film growth.